Tool to convert file to bitstream

3 files changed, 93 insertions, 0 deletions

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..94a873d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+vgcore*
+bitcat
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..476bd96
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,8 @@
+CFLAGS ?= 
+LDFLAGS ?= 
+
+all: bitcat
+
+%: %.c
+	$(CC) -o $@ $< $(CFLAGS) $(LDFLAGS)
+
diff --git a/bitcat.c b/bitcat.c
new file mode 100644
index 0000000..1d4599f
--- /dev/null
+++ b/bitcat.c
@@ -0,0 +1,83 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdarg.h>
+
+#define ISFLAG(str, fshort, flong) (!strcmp(str, fshort) || !strcmp(str, flong))
+
+const char *usage = "USAGE: bitcat [-s SKIP] [-n COUNT] FILE\n";
+
+void
+die(const char *fmtstr, ...)
+{
+	va_list ap;
+
+	va_start(ap, fmtstr);
+	vfprintf(stderr, fmtstr, ap);
+	va_end(ap);
+
+	exit(EXIT_FAILURE);
+}
+
+int
+main(int argc, const char **argv)
+{
+	unsigned char byte, bit;
+	size_t skip, size, pos;
+	const char *filepath;
+	char *end;
+	FILE *f;
+	int i;
+
+	if (argc <= 1) die(usage);
+
+	filepath = NULL;
+	size = skip = 0;
+	for (i = 1; i < argc; i++) {
+		if (ISFLAG(argv[i], "-s", "--skip")) {
+			if (i++ == argc - 1) goto missing_arg;
+			skip = strtol(argv[i], &end, 0);
+			if (end && *end) goto bad_arg;
+		} else if (ISFLAG(argv[i], "-n", "--count")) {
+			if (i++ == argc - 1) goto missing_arg;
+			size = strtol(argv[i], &end, 0);
+			if (end && *end) goto bad_arg;
+		} else if (ISFLAG(argv[i], "-h", "--help")) {
+			die(usage);
+		} else if (*argv[i] == '-') {
+			die("Unknown flag: %s\n", argv[i]);
+		} else if (filepath) {
+			die("Too many files specified\n");
+		} else {
+			filepath = argv[i];
+		}
+	}
+
+	if (!filepath)
+		die("No file specified\n");
+
+	if (!(f = fopen(filepath, "r")))
+		die("Failed to open file\n");
+
+	if (!size) {
+		fseek(f, 0, SEEK_END);
+		size = ftell(f) * 8;
+		fseek(f, 0, SEEK_SET);
+	}
+
+	for (pos = 0; pos < size + skip && !feof(f); pos++) {
+		if (pos % 8 == 0) byte = fgetc(f);
+		bit = (byte >> (pos % 8)) & 1;
+		if (pos >= skip) putchar(bit ? '1' : '0');
+	}
+
+	fclose(f);
+
+	return EXIT_SUCCESS;
+
+missing_arg:
+	die("Flag %s expects an argument\n", argv[i]);
+
+bad_arg:
+	die("Argument has unexpected value: %s\n", argv[i]);
+}